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Tier 2 Assessment

The purpose of Tier 2 assessment is to collect additional site-specific data and, with the use of Tier 2 fate and transport modeling, determine what actual and potential receptors could be impacted by chemicals of concern.

A Tier 2 Site assessment must be conducted and a Site Cleanup Report submitted for all sites when any of the following conditions occur:

  • Free phase petroleum product is present at the site.
  • The site owner or tank owner/operator has decided to bypass the Tier 1 assessment and go directly to the Tier 2 assessment phase.
  • A pathway has failed the Tier 1 assessment.
  • During drilling, bedrock was encountered before groundwater.
  • Explosive vapor levels were measured during a Tier 1 assessment or recent investigation of the site.

Tier 2 Guidance along with software will help you to fill out the assessment report.

Please note the Tier 2-SMR v2.51 User’s Manual and executable files are large documents and may take some time to download from the web site.  If you would like a CD copy of Version 2.51, contact Dawn Santa Maria at 515-725-8365 or Dawn.SantaMaria@dnr.iowa.gov.

Please note the Tier 2-SMR v3.00 executable files may take some time to download from the web site.  If you would like a CD copy of Version 2.51, contact Dawn Santa Maria at 515-725-8365 or Dawn.SantaMaria@dnr.iowa.gov.

For new leaking underground storage tank sites undergoing the Iowa risk based corrective action process that results in a Tier 2 Site Cleanup Report needing to be completed, the Tier 2 Software Version 3.00 should be used.  This does not apply to non-granular bedrock and granular bedrock sites. This is effective May 22, 2010.

Instructions for downloading from the web site are provided below. These instructions are specific to those who have already completed the download / install process for v2.51 of the software.

 

Note that you are able to open files created under v.2.51.  The user input parameters will remain the same from previous versions (K, Sw, W, groundwater flow direction, etc.).  However, the output (i.e., specifically RID plumes and SSTLs) will change based on the recalibrated version of the model.  You will need to review the output information generated from v.3.00 to determine what modifications need to be made (check RID plumes, SSTLs, candidate monitoring wells to see if those selected still meet criteria for S, T,G, etc).  

Please reference the associated Risk Based Tier 2 Software Model v.3.00 Guidance, and Model Transition Rules for guidance on when it is appropriate to use the new model.  When you save project files for submittal to DNR using v3.00, please include the LUST number, date, and v3 in the name of the files being saved (e.g., 9lta04SMRv3_022410.tv2) 

For new leaking underground storage tank sites undergoing the Iowa risk based corrective action process that results in a Tier 2 Site Cleanup Report needing to be completed, the Tier 2 Software Version 3.00 should be used.  This does not apply to non-granular bedrock and granular bedrock sites. This is effective May 22, 2010.


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